By Ranger Steve Mueller
Many people hope to attract Eastern Bluebirds to their yards. Bluebirds prefer moderate to large open areas. I maintain an open area in the backyard just large enough for bluebird acceptance. Now in early June they are starting a second brood for the year.
You can help bluebirds raise successful broods. Water is near by so it is not a critical concern but birdbaths are welcomed. Adequate food is essential. Bluebirds eat a large quantity of fruits and berries during the year and feed heavily on insects during the summer. Young are raised on an insect protein diet so maintain yards with rich insect populations.
During the 1950’s and 1960’s bluebird populations declined dramatically due to the use of pesticides like DDT. They were outlawed in the United States in the 1970’s. Since then bluebird populations have made good recovery. The neighbors changed pesticides allowed for use on crops. Some people do not like neighbors (government) regulating the use of pesticides because it takes away personal freedom. Unrestricted use takes away human life. Pesticides like DDT in human breast milk are not healthy. I substitute the word neighbors for government because it puts a face on who is really creating laws to balance, protect and benefit both society and individual rights.
Bluebirds are cavity nesters seeking hollow trees near open areas. People excessively remove dead trees from woodlots for firewood or to prevent a dead tree from falling and injuring someone. Cleaning the forest of dead trees prevents bluebirds and about 35 species of cavity nesting birds from successful breeding. Placing bluebird boxes throughout the area helps bluebird populations recover. Appropriate shelter remains an important limiting factor preventing bird-nesting success. Allowing dead trees to stand benefits nature niches. It is better to thin live trees from the forest than to cut dead trees. Thinning live trees allows remaining trees to grow healthier and faster. Some removal of dead trees for safety is needed.
Placement of nest boxes is critical. European Starlings are an abundant exotic species that kills bluebirds and other cavity nesters to use a cavity themselves. Keeping the cavity opening to 1 ¼ inch diameter prevents starling entrance. House sparrows are another exotic that enters and kills bluebirds and they enter a cavity hole the size needed for bluebirds. To reduce house sparrow predation, place nest boxes on post well away from trees and shrubs. House sparrows prefer to stay near woody vegetation.
When a nest box is placed in a large open area it appeals to Tree Swallows and they will compete with bluebirds for a nest cavity. Placing two nest boxes 12 to 15 feet apart can solve this problem. Tree swallows take one box and prevent other swallows from using the second box but they do not mind if bluebirds use it. Beyond 15 feet other swallows may compete with bluebirds for the nest box.
One additional nest box precaution. Place a predator guard over the entrance hole. Place a second board with a hole over the access to make it deeper. When a raccoon reaches in for eggs or young, it cannot bend its leg to reach them. Raccoons have become excessively abundant and are a major threat to successful nesting.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at the firstname.lastname@example.org Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433.